Just over two years ago, the critics lined up to question Lewis Hamilton's sanity.

His decision to end a 14-year association with McLaren and join Mercedes was met with scorn - after all, Mercedes had won just one race in three seasons following their return to Formula One in 2010 as a manufacturer.

Hamilton had been nurtured by McLaren from the age of 13 and then groomed to be a world champion, a dream he realised in 2008 after falling a single point shy the previous year

Those startling two years suggested here could be someone to perhaps emulate McLaren great and Hamilton's personal hero Ayrton Senna, whose three titles were all achieved with the team.

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Saturday qualifying

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Saturday third practice

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Saturday third practice

Red Bull are saying goodbye to Sebastian Vettel as he prepares to leave at the end of the season

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Saturday third practice

Prince Harry shares a joke with Geri Halliwell in the Red Bull garage

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Saturday third practice

Adrian Sutil runs his Sauber close to the kerb

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Friday second practice

Lewis Hamilton of Great Britain and Mercedes GP powers on

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Friday second practice

Romain Grosjean of France and Lotus drives the Yas Marina Circuit

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Friday second practice

Paddy Lowe, Mercedes Technical Executive Director looks on in the team garage

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Friday first practice

Fernando Alonso follows his former team-mate Felipe Massa

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Friday first practice

Lewis Hamilton ended first practice on top of the timesheets

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Friday first practice

Romain Grosjean turns in as his Lotus glistens in the Abu Dhabi sun

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Friday first practice

Kamui Kobayashi competes in first practice as Caterham return to action following two races away from the grid

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Friday first practice

Daniel Ricciardo runs through the tunnel in the final sector of the Yas Marina track

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Friday first practice

Lewis Hamilton tackles the Yas Marina circuit

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Friday first practice

Nico Rosberg appears relaxed ahead of the biggest weekend of his life

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Friday first practice

Fernando Alonso poses in the garage ahead of first practice

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Friday first practice

Daniel Riccardo's helmet for the Abu Dhabi Grand Prix

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Friday first practice

Sebastian Vettel signs autographs for fans in his final outing for Red Bull

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But by the end of 2012, Hamilton had gone four more years without another championship to his name.

He had a sniff of glory in 2010 when he went into the final race of the season as the outsider in a four-horse race and in need of a miracle which never happened.

Two years ago Mercedes' non-executive chairman Niki Lauda - like Senna a three-times champion - spoke to Hamilton and convinced him he could again become an F1 force if he jumped ship from McLaren.

If Hamilton was initially sceptical, he was soon won over. Hamilton was deemed foolish by some, who felt this was a clear sign that his occasionally suspect temperament had got the better of him.

Hamilton has openly admitted to wanting to emulate Ayrton Senna's three title wins

Karting and motor racing was Hamilton's staple diet throughout his formative years, with father Anthony at one stage holding down three jobs to ensure his son could follow a path seemingly written in the stars.

Girlfriends and going out with mates were simply not on the agenda.

When McLaren confirmed at the end of 2006 that Hamilton would make the step up to F1 the following year at the age of 22, it was clear then all the sacrifice and pain had been worthwhile.

Six years with McLaren followed, during which time you could sense Hamilton was trying to find himself, to discover his true identity after many years cocooned in his motorsport bubble.

The 'on, off, on again' nature of that relationship, combined with the bitter and public fall-out with his dad at the start of 2010 undoubtedly played on his mind at times and occasionally affected Hamilton's form on track.

The move from McLaren to Mercedes was another opportunity to shake off the last few shackles, with Mercedes prepared to afford him the kind of freedom he had not previously experienced. Over the past two years Hamilton has matured, both on and off track.

The 'playboy' tendencies have disappeared, and while there might still be trappings of wealth, such as his private jet and the gold jewellery, he appears far more grounded these days.

Hamilton is now reconciled with his father and settled with Nicole, two key ingredients behind his improvement at the wheel.

Hamilton's first year with Mercedes in 2013 was one of growth and of learning, with the team having primarily moulded themselves around the needs and suggestions of seven-times champion Michael Schumacher.

With a car more suited to his tastes this season, and with Mercedes head and shoulders above rivals Ferrari and Renault mechanically, Hamilton's talent and the team's development capabilities have combined to finally help him become a Formula One world champion for a second time.

It has arguably cost him a friendship as he and Mercedes team-mate Nico Rosberg, once close as teenagers, have now suffered a parting of the ways as adults and rivals.

Hamilton, though, will not care as he can now step forward and have the last laugh on those who dared to claim he was so foolhardy in 2012.